The present invention relates to an electrophotographic copying apparatus and more particularly, to a copy paper separating device for use in an electrophotographic copying apparatus.
Commonly, in electrophotographic copying apparatuses in which copy paper is adapted to be attracted to or adhere onto the surface of a photosensitive member or photoconductive photoreceptor for transferring an electrostatic latent image or developed toner powder image of an original formed on the photoreceptor surface onto the copy paper in a known manner, it is necessary to separate the copy paper from the photoreceptor surface after the transfer.
Conventionally, for separating the copy paper in the above described manner, there have mainly been proposed separating devices in which a separating claw or the like is arranged to contact the photoreceptor surface at all times or intermittently only during separation for peeling off the leading edge of the copy paper. In the known arrangement as described above, however, since the separating claw is fixed or stationary with respect to the widthwise direction of the photoreceptor surface, it always contacts the photoreceptor surface at the same locus. Therefore, the separating claw is arranged to lightly contact the photoreceptor surface by being urged thereagainst by spring means or balancing by a weight, etc., but still tends to damage part of the photoreceptor surface to form a stripe thereon due to repeated contacts therewith, with consequent reduction of the life of the photoreceptor.
In order to overcome the disadvantages as described above, the present applicants have proposed a transfer paper separating device, for example, in Japanese Laid Open Utility Model Application Jikkaisho 51-43136, in which the separating claw is adapted to move in a widthwise direction of the photoreceptor surface for uniform contact at positions dispersed over a wide range of the photoreceptor surface so as to protect the photoreceptor surface from being damaged at one position and to prolong the life of the photoreceptor. Similarly, for heat roller fixing devices of the electrophotographic copying apparatuses in which the copy paper is passed between a pair of fixing or heat rollers for fixing the toner powder image transferred onto the copy paper by heating, a separating claw and the like is adapted to contact the surface of one of the fixing rollers at all times or intermittently only during the separation to peel off the copy paper closely adhering to the surface of the fixing roller by engagement with the leading edge thereof in a manner similar to that for the photoreceptor for preventing the copy paper from winding around the fixing roller. Since the arrangement as described above also has a tendency to damage the coating layer formed on the fixing roller surface by the tip of the separating claw in the long run, thus resulting in uneven fixing, there has also been proposed a similar separating device, for example, in Japanese Utility Model Publication Jikkosho 53-39237.
In the known arrangements as described in the foregoing, however, since pivoting means for causing the separating claw selectively to contact or be spaced from the photoreceptor surface or fixing roller, and shifting means for moving the separating claw in the widthwise direction of the photoreceptor surface or fixing roller are provided independently, the separating device itself tends to have a large size and a complicated structure, thus involving troublesome procedures in assembly and adjustments thereof.